Microscopy Boot Camp 2009 2009/08/25 Nikitchenko Maxim Baktash Babadi
Dec 17, 2015
Plan of the lecture
• Basic properties of light• Light/matter interaction• Wide-field microscopy• Scanning microscopy• EM• Ultra-high resolution microscopy• Dyes
Part 1
Part 2
Part 3
Corpuscular/wave dualism
www.olympusmicro.com
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Diffraction
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Basic electromagnetic wave properties
• Amplitude• Wavelength• Frequency• Phase• Polarization
hyperphysics.phy-astr.gsu.edu
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
)sin(0 tkzEE
Polarization
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Light/matter interaction
• Particles point of view: Absorption
Emission Scattering
• Waves point of view:Refraction
ReflectionAbsorptionDiffraction (Change of Phase and Polarization)
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Optics of a thin lens (1)
Focus
d F
F CC F
C=2F
0F
dThin Lens:
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Optics of a thin lens (2)• Three different scenarios:
F 2F2F F
F 2F2F F
F 2F2F F
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Optics of a thin lens (3)
f
p q
F CC F
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Compound Microscope
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Basic optical structure of a microscope
objective
specimen
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
eyepiece
Specimen Illumination System
• Parts– Specimen plane
– Condenser
– Diaphragm
– Light Source
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Microscope Illumination Conditions:
• Critical illumination– The condenser focuses
the light onto the specimen plane
Filament image effect
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Köhler illumination
• The specimen is illuminated homogenously
• The specimen and the images of the light source are in different planes
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Types of Microscopy
• Bright Field (absorption)
• Dark Field (scattering)
• Phase-contrast (phase change)
• Polarization (scattering by birefringent specimen)
• Differential interference contrast (DIC) (gradients of optical thickness)
• Fluorescent (frequency change as a result of absorption/emission by fluorophores)
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Dark field Microscopy
uses the difference in scattering abilities
block out the central light rays (leave oblique only)
Result: only highly diffractive and scattering structures are seen
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Dark-Field example
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
uses the λ/4 phase change when light passes through thin structures
Similar oblique illumination to the Dark Field method
The specimen diffracts some of the light that passes through it and introduces phase lagging λ/4
A phase difference (λ/2) is introduced between background and diffracted light (using phase plate) → destructive interference
Phase Contrast Microscopy
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Phase Contrast Microscopy
• Suitable for unstained specimens
Human glial cells
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Polarization MicroscopyUses polarization property of
light and birefringence• Polarizer polarizes light• Analyzer passes only the light
with polarization perpendicular to the source light
Birefringent material introduces 2 perpendicularly polarized components, propagating at different speed in the specimen → Δφ
• Constructive interference following analyzer is possible only for phase shifted light
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Polarized microscopy example
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Differential Interference Contrast (DIC) (Nomarski optics)
• Addon to the polarization microscopy
• Wollaston prism generates 2 || beams, π/4 polarized to polarizer and laterally displaced (this is the difference to polarization microsc., endowing optical density gradient sensitivity)
• The rest is similar to pol. Micr. (except for 2nd Wollaston prism)
• Result: good for edge detection
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Nomarski optics principle
polarizer
Beam
Splitter
shear
condenser
specimen
objective
combiner
analyzer
intensity
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
DIC example
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Fluorescent Microscopy (1)
• Fluorescence– Emission light has longer wavelengths than
the excitation light: Stokes shift.
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Fluorescent Microscopy (2)
• Types of Fluorescence– Auto-Fluorescence (Plants, Fungi,
Semiconductors, etc)– Fluorescent dyes
• Fluorochromes (Flurescein, Acredine Orange, Eosin, Chlorophyll A, … )
• Genetically coded (GFP, YFP,…)
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Fluorescent Microscopy (3)
• The basic task of the fluorescence microscope:– Illuminate the specimen with excitation light– Separate the much weaker emission light
from the brighter excitation light. – Only allow the emission light to reach the
eye or other detector.– The background is dark, the fluorescent
objects are bright
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Epi-Fluorescent Illumination
• The emission light does not pass through the specimen
• The objective acts as the condenser
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Fluorescent Microscopic images (1)
Human cortical neurons Human brain glioma cells
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Fluorescent Microscopic images
Fluorescence/DIC combination, cat brain tissue infected with Cryptococcus
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Brainbow
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Selection of the microscopeIs it thin? (<50 microns)
Is it reflective?e.g. gold, silver
Is it fluorescent?
Confocal
Epi-fluorecenceIs it fluorescent?
Is it colored, densely contrasted or stained?
Is it transparent?
Bright field
Phase contrast, DIC
Is it reflective?e.g. gold, Silver
Is it birefringent? Polarization
Dark field
no
no
no
no
no
noyes
yes
yes
yes
yes
yes
yes
Basic Properties of Light Thin lenses Wide-field Microscopy Fluorescent Microscopy Microscope selection
Rubbi, C.P., 1994